The disclosure relates generally to a power generation system and more specifically to improved response time of a braking unit in a power generation system.
Typically, when a fault in a utility system occurs, voltage in the utility system may suddenly decrease by a certain amount. This sudden decrease of the voltage may result in a sudden reduction of an electrical power output of a generator. As a consequence, there may be unbalance between the electrical power output of the generator and mechanical power input from an engine. This in turn causes acceleration of the generator, which may lead to loss of synchronism between the generator and an electrical grid. Also, stability of the electric grid may be jeopardized if the generator is disconnected. It is therefore desirable for the generators to remain synchronized to the grid, to ride through low voltage conditions, and to be able to feed electric power into the grid immediately after the fault is cleared.
Various techniques may be employed to overcome the issue of rapid acceleration in the generator during fault conditions. One such technique is to employ a braking unit in a power generation system to control speed of a rotor in the generator. In one example, the braking unit includes one or more coils that are disposed proximate to the rotor, and, when a voltage is applied to these coils, electromagnetic braking force is induced on the rotor such that the speed of the rotor is controlled accordingly. Due to the inductive nature of the coils, the rate of change in the electrical current in the coils is limited by the applied voltage and may require a longer than desired braking response time. To improve the response time, a higher voltage power source may be coupled to the coils. However, such power source would increase the cost and size of the braking unit and may be impractical.
Hence, there is a need for an improved system and method for providing effective and inexpensive electromagnetic brakes on the rotor. Also, there is a need to provide a braking unit having a fast response time.